Abstract #3171

Detection of Macrophage Accumulation After Heart Transplantation in a Rat Using a Novel Nano-Sized Iron Oxide Particle with High Relaxivity

Haosen Zhang¹, Chih-Lung Chen², Qing Ye¹, Kevin Hitchens¹, Wen-Yuan Hsieh², Hsiu-Hua Huang², Yi-Shan Lin², HsinHsin Shen², Mu-Jen Young², Wei-Lin Yu², Ying-Ting Huang², Lesley Foley¹, Yijen Wu¹, Jassy Wang², Chien Ho¹

¹Pittsburgh NMR Center for Biomedical Research, Department of Biological Science , Carnegie Mellon University, Pittsburgh, PA, USA; ²Industrial Technology Research Institute, Taiwan

The aim of this study was to detect the macrophage accumulation by in vivo MRI in a rat heterotopic heart transplantation model of acute rejection using a biodegradable, nano-sized iron oxide particle with high relaxivity. After being labeled ex vivo with ITRI-IOP, punctuate spots of hypointensity were observed on the mid-wall of the transplant heart 24 hrs post injection. Ex vivo imaging of the fixed heart demonstrated abundance of punctuated spots of hypointensity that might be caused by the iron-loaded macrophages. Histological analysis and iron staining confirmed the presence of iron and macrophages in the corresponding tissue section as MRI.